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Abstract:

In an exemplary embodiment, the present invention provides an orthopedic
plate blocking assembly that can be used for the fixation or fastening of
an orthopedic plate to bone tissue. In particular, the present invention,
in one embodiment, provides an orthopedic plate having a plurality of
cavities where each cavity is configured and dimensioned to receive a
bone anchoring member. The orthopedic plate further provides a blocking
mechanism having a plurality of blocking members that block the bone
anchoring members to prevent the bone anchoring members from "backing
out" of cavities once the bone anchoring members are finally seated in
the cavities.

Claims:

1. An orthopedic plate assembly, comprising: a plate member adapted to be
fastened to bone tissue, the plate member having an upper surface and a
lower surface; a plurality of cavities extending from the upper surface
to the lower surface of the plate member, each cavity being configured
and dimensioned to receive a bone anchoring member; a plurality of bone
anchoring members, each bone anchoring member having a bone engaging end
and being configured and dimensioned to be received within a cavity to
fasten the plate to the bone tissue; a first blocking member located on
the plate member and capable of restraining a bone anchoring member from
axial movement in a second blocking position and allowing axial movement
of the bone anchoring member in a first non-blocking position; and a
second blocking member located on plate member and capable of restraining
a bone anchoring member from axial movement in a second blocking position
and allowing axial movement of the bone anchoring member in a first
non-blocking position, wherein actuation of the first blocking member
from the first non-blocking position to the second blocking position also
results in actuation of the second blocking member from the first
non-blocking position to the second blocking position, wherein the first
and the second blocking members have a plurality of gear teeth extending
along at least a portion of the circumference of the first and second
blocking members.

2. The plate assembly of claim 1, wherein the first and second blocking
members are rotatably actuatable.

3. The plate assembly of claim 1, wherein the shaft portion of each
blocking member includes threading extending along at least a portion of
its length for engaging the plate member.

4. The plate assembly of claim 1, wherein the shaft portion of each
blocking member includes a swaged tip at one end for engaging the plate
member.

5. The plate assembly of claim 1, wherein the diameter of a head portion
of each blocking member increases in a non-linear fashion from a first
end of the head member to a second end of the head member.

6. The plate assembly of claim 1, wherein gear teeth of the first
blocking member engage with the gear teeth of the second blocking member
such that actuation of the first blocking member results in actuation of
the second blocking member.

7. The plate assembly of claim 5, wherein the head portion of each
blocking member includes an access cut portion extending along a portion
of the circumference of the head portion.

8. The plate assembly of claim 1, wherein the at least one blocking
member includes an opening for receiving a driving instrument.

9. The plate assembly of claim 1, wherein the bone anchoring member
includes a head portion having a generally spherical shape.

10. An anchor assembly system for fastening an orthopedic plate to bone
tissue, comprising: a plurality of bone anchoring members, each bone
anchoring member comprising a head portion having a generally spherical
shape, a shank portion for engaging the bone tissue, and a neck portion
for connecting the head portion and the shank portion; a plate member
having a plurality of cavities, each cavity configured and dimensioned to
receive a bone anchoring member; and a blocking mechanism having a
plurality of blocking members located on the plate member, each of the
blocking members being engaged to at least one other blocking member,
wherein the blocking mechanism is rotatably actuatable from a first
position where the plurality of cavities are unblocked and the plurality
of bone anchoring members can be removed from the plurality of cavities
to a second position where the plurality of cavities are blocked and the
plurality of bone anchoring members cannot be removed from the plurality
of cavities, wherein each blocking member has a plurality of gear teeth
extending along the circumference of the blocking members.

11. The anchor assembly system of claim 10, wherein at least one blocking
member is located adjacent a cavity.

12. The anchor assembly of claim 10, wherein a shaft portion of each
blocking member includes threading extending along at least a portion of
its length for engaging the plate member.

13. The anchor assembly of claim 10, wherein the shaft portion of each
blocking member includes a swaged tip at one end for engaging the plate
member.

14. The anchor assembly of claim 10, wherein the diameter of a head
portion of each blocking member increases in a non-linear fashion from a
first end of the head member to a second end of the head member.

15. The anchor assembly of claim 10, wherein the gear teeth of the first
blocking member engage with the gear teeth of the second blocking member
such that actuation of the first blocking member results in actuation of
the second blocking member

16. The anchor assembly of claim 14, wherein the head portion of each
blocking member includes an access cut portion extending along a portion
of the circumference of the head member.

17. The anchor assembly of claim 10, wherein the at least one blocking
member includes an opening for receiving a driving instruments

18. An orthopedic plate assembly, comprising: a plate member adapted to
be fastened to bone tissue, the plate member having an upper surface and
a lower surface; a plurality of cavities extending from the upper surface
to the lower surface of the plate member, each cavity being configured
and dimensioned to receive a bone anchoring member; a plurality of bone
anchoring members, each bone anchoring member having a bone engaging end
and a spherical head portion, wherein a bone anchoring member is
configured and dimensioned to be movably received within the cavity to
fasten the plate to the bone tissue; a first blocking member located on
the plate member and capable of restraining a bone anchoring member from
axial movement in the second blocking position and allowing axial
movement of the bone anchoring member in the first non-blocking position;
and a second blocking member located on plate member and capable of
restraining a bone anchoring member from axial movement in the second
blocking position and allowing axial movement of the bone anchoring
member in the first non-blocking position, wherein the first blocking
member and second blocking member each have a head portion and a shaft
portion, each head portion having plurality of gear teeth extending along
at least a portion of the circumference of the head member, wherein the
gear teeth of the first blocking member engage with the second blocking
member, and wherein rotational actuation of the first blocking member
from the first non-blocking position to the second blocking position also
results in rotational actuation of the second blocking member from the
first non-blocking position to the second blocking position.

Description:

CROSS-REFERENCE TO RELATED APPLICATIONS

[0001] This patent application is a continuation application of U.S.
patent application Ser. No. 12/466,721 filed on May 15, 2009, which is
incorporated by reference in its entirety herein.

FIELD OF THE INVENTION

[0002] The present invention is directed to orthopedic plates and, in
particular, to a blocking assembly for securing an orthopedic plate to
bone tissue.

BACKGROUND OF THE INVENTION

[0003] The use of orthopedic plates for correction of spinal deformities
and for fusion of vertebrae is well known. Typically, a rigid plate is
positioned to span bones or bone segments that need to be supported or
immobilized with respect to one another. The orthopedic plate is fastened
to the bone tissue with bone anchors or screws so that the plate remains
in contact with and supports the bone or bone segments.

[0004] However, the structure of spinal elements presents unique
challenges to the use of orthopedic plates for supporting or immobilizing
vertebral bodies. Among the challenges involved in supporting or fusing
vertebral bodies is the effective installation of an orthopedic plate
that will resist migration despite the rotational and translational
forces placed upon the plate resulting from spinal loading and movement.
For a plate to work effectively in such an environment the bone anchors
or screws must be properly positioned and anchored within the bone.

[0005] Furthermore, over time, it has been found that as a result of the
forces placed upon the orthopedic plate and anchors resulting from the
movement of the spine and/or bone deterioration, the orthopedic anchors
can begin to "back out" from their installed position eventually
resulting in the fasteners disconnecting from the plate.

[0006] As such, there exists a need for an orthopedic plate that provides
for the proper placement of the bone anchor or screws and provides a
mechanism where the bone anchors are blocked to prevent the anchors from
"backing out" of their installed position

SUMMARY OF THE INVENTION

[0007] In an exemplary embodiment, the present invention provides an
orthopedic plate blocking assembly that can be used for the fixation or
fastening of an orthopedic plate to bone tissue. In particular, the
present invention, in one embodiment, provides an orthopedic plate having
a plurality of cavities where each cavity is configured and dimensioned
to receive a bone anchoring member. The orthopedic plate also provides a
blocking mechanism having a plurality of engaged blocking members that
block the bone anchoring members to prevent the bone anchoring members
from "backing out" of cavities once the bone anchoring members are
finally seated in the cavities.

[0008] Further areas of applicability of the present invention will become
apparent from the detailed description provided hereinafter. It should be
understood that the detailed description and specific examples, while
indicating the preferred or exemplary embodiments of the invention, are
intended for purposes of illustration only and are not intended to limit
the scope of the invention.

BRIEF DESCRIPTION OF THE DRAWINGS

[0009] The present invention will become more fully understood from the
detailed description and the accompanying drawings, wherein:

[0010] FIG. 1 is an exploded partial perspective view of one embodiment of
an orthopedic plate blocking assembly;

[0011] FIG. 1A is a perspective view of a blocking gear included in the
blocking assembly shown in FIG. 1;

[0012] FIG. 2 is top view of the blocking assembly shown in FIG. 1 in an
unblocked position;

[0013] FIG. 2A is a top view of the blocking assembly of FIG. 1 in a
blocking position; and

[0014] FIG. 3 is a schematic cross-sectional view of the blocking assembly
shown in FIG. 1.

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

[0015] The following description of the preferred embodiment(s) is merely
exemplary in nature and is in no way intended to limit the invention, its
application, or uses.

[0016] With reference to FIG. 1, an embodiment of an orthopedic plate
blocking assembly 10 is illustrated. Although not shown in the
environment of use, the orthopedic plate blocking assembly 10 is adapted
to be used for supporting and/or immobilizing adjacent bones or bone
segments, such as vertebrae, in the spine. The blocking assembly 10
preferably includes an orthopedic plate 12, a blocking mechanism 14, and
at least one bone screw 16. Even though only the bone screw 16 is
identified as the fastening or anchoring element, it is contemplated that
the fastening or anchoring element can be any of the following,
including, but not limited to, a hook, a pin, or a nail. Further,
although only two bone screws 16 are shown in FIG. 1, it is contemplated
that the number of screws 16 will correlate to the size of the plate 12.
For example, a smaller plate can include two to four screws whereas a
larger plate can include six or more screws. The blocking assembly 10 is
preferably constructed from any biocompatible material including, but not
limited to, stainless steel, stainless tell alloys, titanium, titanium
based alloys, or polymeric materials.

[0017] Looking at FIG. 1, in one embodiment, the screw 16 includes,
concentric to a longitudinal axis, a head portion 18, a neck portion 20
and a shank portion 22. The head portion 18 connects to the shank portion
22 through the neck portion 20. Preferably, the head portion 18 of the
screw 16 has a cavity 17 for receiving a driving instrument 19. The head
portion 18 also has a generally spherical shape that is configured and
dimensioned to be received within a correspondingly shaped cavity 24 in
the orthopedic plate 12. The shape of the head portion 18 and the
correspondingly shaped cavity 24 allow the screw 16 to pivot, rotate
and/or move with respect to the orthopedic plate 12. In another
embodiment, instead of allowing the screw 16 to pivot, rotate and/or move
with respect to the orthopedic plate 12, the head portion 18 and the
correspondingly shaped cavity 24 may be configured and dimensioned to
keep the screw 16 in a fixed position with respect to the plate 12.

[0018] In an exemplary use, after the head portion 18 of the screw 16 is
received in the cavity 24 of the orthopedic plate 12, the screw 16 can be
pivoted, rotated or moved until the desired orientation with respect to
the orthopedic plate 12 is met. This functionality allows the screw 16 to
be anchored into the bone tissue at the desired orientation and placement
with respect to the orthopedic plate 12 maximizing the ability of the
plate 12 to resist migration in spite of the rotational and translational
forces placed upon the plate from spinal loading and movement. One of
ordinary skill in the art would recognize that the screw 16 is anchored
into the bone tissue by driving the screw 16 into the bone tissue via
driving instrument 19 interfacing with the cavity 17. The screw 16 is
then blocked in place, which is discussed in detail below, in the cavity
24 of the orthopedic plate 12.

[0019] With continued reference to FIG. 1, in one embodiment, the neck
portion 20 of the screw 16 integrally connects the head portion 18 with
the shank portion 22. The shank portion 22 of the screw 16 includes a
shaft 26 surrounded at least in part by a thread portion 28. In one
embodiment, the diameter of the shaft 26 remains generally constant from
a proximal end of the shaft 26 toward a distal end of the shaft 26. The
constant diameter of a majority portion of the shaft 26 allows for
optimal screw positioning when the screw 16 is inserted into a
predetermined area in the bone tissue. The constant diameter also allows
for varying the depth positioning of the screw 16 in the bone. For
example, if a surgeon places the screw 16 into bone tissue at a first
depth and decides the placement is more optimal at a second, shallower
depth, the screw 16 can be backed out to the second depth and still
remain fixed in the bone. In another embodiment, the diameter of the
shaft 26 may vary along its length, including increasing in diameter from
the proximal end to the distal end or decreasing in diameter from the
proximal end to the distal end.

[0020] The thread portion 28 surrounding the shaft 26 extends, in a
preferred embodiment, from the distal end of the shaft 26 to the neck
portion 20. In another preferred embodiment, the thread portion 28 may
extend along only a portion of shaft 26. The thread portion 28 is
preferably a Modified Buttress thread but the thread can be any other
type of threading that is anatomically conforming, including, but not
limited to Buttress, Acme, Unified, Whitworth and B&S Worm threads.

[0021] In a preferred embodiment, the diameter of the thread portion 28
decreases towards the distal end of the screw 16. By having a decreased
diameter thread portion 28 near the distal end of the screw 16, the screw
16 can be self-starting. In another preferred embodiment, screw 16 may
also include at least one flute to clear any chips, dust, or debris
generated when the screw 10 is implanted into bone tissue.

[0022] Turning to FIGS. 1-3, the blocking assembly 10 includes the
blocking mechanism 14. The blocking mechanism 14 will block the screws 16
with respect to the orthopedic plate 12 thereby preventing the screws 16
from disengaging or "backing out" from the orthopedic plate 12. In one
embodiment, the blocking mechanism 14 includes at least a leader blocking
gear 30 and a follower blocking gear 32, each of which are configured and
dimensioned to be received in openings 34, 36 in the orthopedic plate 12.
Although only one leader blocking gear 30 and one follower blocking gear
32 are shown in FIG. 1, it is contemplated that for at least every two
screws 16, there is at least one leader blocking gear 30 and at least one
follower blocking gear 32. Alternatively, for multiple screws, there can
be one leader blocking gear and a plurality of follower blocking gears.
For example, there can be one leader blocking gear and plurality of
follower blocking gears, where the leader blocking gear is positioned
adjacent one screw, some of the plurality of follower blocking gears are
positioned adjacent to the other screws, and some of the plurality of
follower blocking gears serve to bridge the leader blocking gear and the
follower blocking gears that are positioned adjacent the screws.

[0023] Focusing now on FIG. 1A, even though the following discussion is
limited to the leader blocking gear 30, it is important to note that the
following discussion is equally applicable to the follower blocking gear
32 as the structure of the follower blocking gear 32 is substantially
identical to the leader blocking gear 30. In one embodiment, the leader
blocking gear 30 has, concentric to a longitudinal axis, a head member 38
and a shaft member 40. The head member 38 preferably includes an opening
42 for receiving a driving instrument 19 and a variable diameter where
the diameter of the head member 38 preferably increases in a non-linear
fashion from the bottom end of the head member 38 to the top end of head
member 38. The variable diameter of the head member 38 defines the shape
of the head member 38 such that it can accommodate the spherically shaped
head portion 18 of the screw 16 allowing the screw 16 to move with
respect to the plate 12 but still block the screw 16 from disengaging or
"backing out" from the plate 12. In one embodiment, the head member 38
also includes a plurality of gear teeth 44 extending along at least a
portion of the circumference of the head member 38 and a cutout or access
cut portion 46 extending along a portion of the circumference of the head
member 38. In one embodiment, the shaft member 40 can include threading
48 extending along at least a portion of its length for engaging the
orthopedic plate 12. Alternatively, as best seen in FIG. 3, the shaft
member 40 may not have any threading, but can have a swaged tip 49 for
engaging the orthopedic plate 12. The leader blocking gear 30 and the
follower blocking gear 32 are positioned on the orthopedic plate 12 so
that the gear teeth 44 on the blocking gears 30, 32 interdigitate
allowing the leader blocking gear 30, when rotated, to rotate the
follower blocking gear 32.

[0024] In an exemplary use of the orthopedic plate blocking assembly 10,
the orthopedic plate 12 is oriented and placed in the area of treatment.
The orthopedic plate 12 is then fastened to the bone tissue via at least
one screw 16 which is received in at least one cavity 24 of the
orthopedic plate 12. The screw 16 passes through the cavity 24 until the
head portion 18 of the screw 16 is seated in the cavity 24. In an
exemplary use, a plurality of screws 16 are received through the cavities
24 and are fastened to the bone tissue to fasten the plate 12 to the bone
tissue.

[0025] As best seen in FIGS. 2-3, once the screws 16 are seated in the
cavities 24, the screws 16 can be blocked to prevent the screws 16 from
disengaging or "backing out" from the cavities 24 by actuating the
blocking mechanism 14. Focusing on FIGS. 1 and 2, in one embodiment, a
user actuates blocking mechanism 14 by engaging the opening 42 with the
driving instrument 19 and using the driving instrument 19 to rotate the
leader blocking gear 30 in a first direction from an unblocking position
to a blocking position.

[0026] In the unblocking position, shown in FIG. 2, the leader blocking
gear 30 and the follower blocking gear 32 are positioned such that the
access cut portions 46 of the blocking gears 30, 32 are aligned with the
cavities 24 allowing the screws 16 to enter and exit from cavities 24. As
the leader blocking gear 30 is rotated from an unblocking position to a
blocking position, the follower blocking gear 32 also rotates from an
unlocked or unblocking position to a blocking position since the gear
teeth 44 on the blocking gear 30 are engaged with the gear teeth 44 on
the follower blocking gear 32. The leader blocking gear 32 and the
follower blocking gear 34 are rotated until the access cut portions 46 of
the blocking gears 30, 32 are no longer aligned with the cavities 24.
This is the blocking position of the blocking gears 30, 32 and can best
be seen in FIGS. 2A and 3, where a portion of the head members 38 of the
blocking gears 30, 32 are blocking the screws 16 from disengaging or
"backing out" from cavities 24.

[0027] In order to set the blocking gears 30, 32 back into the unblocking
position, the blocking gears 30, 32 can be rotated in a second direction,
which is opposite to the first direction, until the access cut portions
46 of the blocking gears 30, 32 are again aligned with the cavities 24
allowing the screws 16 to be removed from the plate 12. Alternatively,
the blocking gears 30, 32 can be further rotated in the first direction
until the access cut portions 46 of the blocking gears 30, 32 are again
aligned with the cavities 24 allowing the screws 16 to be removed from
the plate 12.

[0028] The invention being thus described, it will be obvious that the
same may be varied in many ways. Such variations are not to be regarded
as a departure from the spirit and scope of the invention, and all such
modifications as would be obvious to one skilled in the art are intended
to be included within the scope of the following claims.